Solid organ transplantation is the ideal therapy for end stage organ failure including kidney, heart, liver, lung, islet and small bowel. Despite significant improvements in the care of all solid organ transplant recipients and in outcomes following bone marrow transplantation, long term allograft survival remains suboptimal, causes of graft loss and graft vs. host disease are only partially understood, reliable tolerance induction protocols remain elusive, and the ability to translate what information is available into useful diagnostic, preventive and treatment modalities has been limited. In order to continue to improve transplant outcomes in humans and as a consequence, improve the long term health of all transplant recipients, research in transplantation must remain cutting edge, and the next generation of M.D. and Ph.D. physicians/scientists must have the appropriate skills to continue to drive the field forward. Thus, the objective of this institutional postdoctoral T32 application is to use an interactive, collaborative, cross-disciplinary approach to train talented physician-scientists (M.D. and M.D. Ph.D.) or Ph.D.-scientists for successful independent careers in investigative transplantation research. An experienced and well funded group of 20 trainers from a host of departments within the Mt. Sinai School of Medicine, an institution dedicated to supporting basic and translational science, will provide postdoctoral fellows with the opportunity to train in a variety of areas of research related to transplantation. Postdoctoral trainees currently holding a degree of M.D., Ph.D., or M.D. / Ph.D. will be selected for support based on having outstanding potential to pursue a research career and a commitment to independent investigation. Support is requested for 1 postdoctoral trainee in year 1, 2 in year 2 and 3 in years 3-5 of the training application. Training will require a minimum of 2 years. Trainees will participate in an interactive environment with state of the art shared research facilities, involving required courses, a core transplant science seminar series, journal clubs, and laboratory meetings. An internal advisory board will assure that the highest quality applicants will perform transplant oriented research with qualified trainers. The advisory board and an external review group will supplement trainer supervision to ensure that that the program remains cutting edge and that trainees receive sufficient guidance to optimize their transition to independent investigators in transplantation, a field directly relevant to human health.